AV_G103GM_LINES.SHP - Tracklines for multichannel seismic data collected by the USGS in the Atwater Valley area aboard the R/V GYRE Cruise G1-03-GM (03001)

Abstract:

This line shapefile contains navigation of the lines for the multichannel seismic survey that was conducted in the Atwater Valley area of the Gulf of Mexico during USGS cruise G1-03-GM aboard the R/V Gyre in the Gulf of Mexico in May, 2003. The purpose of this cruise was to collect multichannel seismic data in support of USGS and Department of Energy gas hydrate studies. About 253 km of data were collected along 35 short lines in and around lease block Atwater Valley 14 on the floor of the Mississippi Canyon.

Horizontal positions are specified in geographic coordinates, that is, latitude and longitude.
Latitudes are given to the nearest 0.000000.
Longitudes are given to the nearest 0.000000.
Latitude and longitude values are specified in Decimal degrees.

The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.

This GIS overlay is a component of the U.S. Geological Survey, Woods Hole Science Center's, Gulf of Mexico GIS database. The Gulf of Mexico GIS database is intended to organize and display USGS held data and provide on-line (WWW) access to the data and/or metadata.

Navigation file opened in MS Excel, arc milliseconds for X and Y coordinates were converted to decimal degrees (by dividing the each of the arc-millisecond values by 3,600,000 and creating the two new attribute fields X_DD and Y_DD) [excel file ##to##sda.xls]. A header line was added to the table in Excel.

Navigation (corrected with a shift to reflect the shot location) taken back into ProMAX. Then file of CDP locations (g1cdp.nav) exported from ProMAX. File split into kc_cdp.nav and av_cdp.nav, then awk script to reformat the output. CDP points into ArcView 3.3 and saved as shapefiles g1cdp_nav_kc_geo.shp and g1cdp_nav_av_geo.shp.

Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

The SHP file contains the geospatial data. The SHX file contains the index of the geospatial data. The DBF file contains the attribute data in dBase format. The PRJ file contains the coordinate system information (optional). The AVL file contains the legend information (optional). The SBN and SBX files contain the spatial index of the geospatial data (optional). The XML file contains the metadata describing the data set <data set name>.shp.xml. An ASCII version of the metadata file. A browse graphic showing the data layer coverage and extent (optional).
in format SHP
(version 3.3)
ESRI polyline shapefile
Size: 0.742

The data are available in Environmental Systems Research Institute (ESRI) shapefile format. The user must have ArcGIS® or ArcView® 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing data. A free data viewer, arcexplorer, capable of displaying the data is available from ESRI at www.esri.com.